THINK MATH - This part of the site is designed for fourth graders and is organized by topic and skill. There are some demonstration videos along with practice games.
https://www.harcourtschool.com/thinkmath/grade_4.html
The link below is for first graders: https://www.harcourtschool.com/thinkmath/grade_1.html
ESTIMATION CONTRAPTION - Can your brain work like the Estimation Contraption? Well, you will need to round, add while doing mental math, and input your answer to find out. Start out on level one and go to higher levels in order.
MEASURING IN CM AND IN - How are you doing with measuring? In our country we often measure in inches in feet. Scientists and many other countries use the metric system. Remember: a centimeter is about the width of your finger.
FIRST IN MATH - This site has a variety of activities to improve math skills. It's a highly motivating site.
https://www.harcourtschool.com/thinkmath/grade_1.html
A PLUS MATH - Practice your multiplication skills at the same time you improve your memory with these concentration games.
COOL MATH - This site has several math games that will certainly get you thinking!
https://www.mathgames.com/math-games.html
Tons of math games organized by grade and topic.
MATH PLAYGROUND - There are some interactive games to help you practice your facts and develop skills. You'll need to do some tricky mental math for some of these!
MATH MYSTERIES - Calling all math detectives! Mysteries are popping up all over town, and our chief sleuth needs your help to crack each case. Come along on the journey of the Math Maven and solve the mysteries!
http://teacher.scholastic.com/maven/
MR. NUSSABAUM'S WEBSITE - No, I don't know who Mr. Nussbaum is, but I do know that you'll like this site. Get ready for interesting and exciting games!
PLACE VALUE PRACTICE - This is a straight forward practice site for rounding. You will know which place to round to by looking at the underlined digit. Remember, that we estimate when we don't need the exact answer. This happens a lot in life!
MANIPULATIVES THAT ENGAGE - There are TONS of great manipulatives (pattern blocks, geoboards, logopaths-like activities) on this site. You may need to download java or adobe if you don't have them for these to work properly.
MATH IS FUN - This site is split up into different units/topics. You will read about each topic and look at the examples to understand. At the bottom of each section are questions that you should answer to see how well you understand the information.
NUMBER NUT - This site is organized by topics and skills. This site will give you practice with lots of different math concepts.
PLACE VALUE GAMES - There are a bunch of simple games to get your brain thinking about the meaning of digits and the places that they are put in.
ROUNDING - WHO WANTS TO BE A MATHIONAIRE? - Set up like a game show, see how many rounding questions you can answer. Yes, there are life lines, just like the TV show!
ROUNDING PRACTICE - This is a straight forward practicing site. It lets you know which place value to round to by underlining it. Remember, that people estimate when they don't need to know the exact answer.
PRONGO - There are several math games here. The baseball game will challenge you with your mental math!
ROUNDING SHARKS - Help save the goldfish from the sharks. You will only be able to if you can round to the nearest hundred to make the sharks disappear!
XP MATH - There are lots of arcade style games organized by math strand.
TEACHERS' LAB - On this site, you need to figure out the pattern and then prove that you understand it by solving a similar one on your own. If you think of an in/out machine, it may help you.
TENMARKS - Are you ready to push your mathematical thinking? You will have 10 questions about each topic. Don't worry if you get stuck though. There are videos and hints. Then, once you see your score, you can go back and try again. I would highly recommend that you have some paper to do the work on so you are actually determining the answer and not just guessing.